In its current CASSP grant focused on development of services for juvenile offenders South Carolina has demonstrated the efficacy of family preservation services utilizing multisystemic therapy (MST) in preventing out-of-home placement of serious juvenile offenders. The CASSP project has used a true experimental design with collection of data on youth themselves, their families, and the systems with which they are involved. Because the intervention involved in multisystemic therapy is highly flexible (as well as intensive and integrated) and because it differs markedly from office-based interventions for which most mental health professionals are trained, there is a remaining question about whether the intervention can be successfully disseminated. The present project answers that question through replication of the CASSP experiment (conducted in Greenville County) in three other sites in South Carolina: a rural, majority-Black area (Bamberg, Calhoun, and Orangeburg Counties); a rural, majority-White area (Cherokee and Union Counties and southern Spartanburg County); an urban, majority-White area (northern Spartanburg County). Accordingly, the efficacy of the intervention will be tested in diverse sites with variable availability of resources. The project will assess three broad, interrelated levels: (I) short- and long-term effects of MST on the antisocial behavior and psychosocial functioning of serious juvenile offenders; (II) effectiveness of diffusion at successive steps of implementation: (III) systemic effects, including cost-effectiveness.